I have a 2000 Mustang
Someone rear ended me a couple of weeks back and broke my exhaust manifold. Anyway, I got it fixed and the car ran fine.
A week or so after I fixed it, I changed the EGR solenoid because I was checking my motor and it looked like it wasn't working. The car ran way smoother after I changed it.
A couple of weeks after that, I changed the PCV valve and when I did that, my car started idling rough at stop lights. I bought the valve at Discount Auto Parts so I figured maybe it wasn't the right fit. So I went to Ford and bought the Motorcraft valve and replaced it. I checked the PCV hose for leaks or clogs but it was fine. The car still idled rough.
The care actually started running way rougher and then it started sputtering. So I took a look at my exhaust and sure enough, one of the oxygen sensors was ripped - probably from the accident as my manifold actually broke off and I drove 2 or 3 blocks with my oxygen sensors wires holding it.
Anyway, I changed the oxygen sensors and the spark plugs and spark plug wires. The car didn't sputter anymore but it still idles rough. So I decided to change the EGR valve but that didn't help either. The car still idles rough.
I have no CEL light and I'm running out of ideas. I did notice the RPMS go up and down a little when the car is idling at stop lights (not related to the A/C).
At first I thought it was the PCV valve, but I'm starting to think it may be related to my exhaust manifold. it was a used one after all - although the car did idle fine until I replaced the PCV valve. I'm getting frustrated.
You guys got any ideas?